The inspection of tubular workpieces is demanding because, among other things, a sufficient and interference-free coupling of the ultrasound inspection device is rather difficult. Moreover, the intensity of the received signals is very much dependent upon the surface geometry, which is the reason why a test probe is actually proposed in DE 27 40 106 which determines the alignment of two other, outer test probes in accordance with the surface geometry of the workpiece to be inspected, by means of a sound attenuation measurement. This device and the underlying method are complex and cost-intensive.
An inspection device for non-destructive inspection is known from DE 27 51 810, in which a total of six test probes, the sound beams of which intersect in a single point, are arranged in an inspecting spider. The sound-transmitting coupling is carried out by supplying water into the plane of contact. It is a drawback of this arrangement that the coupling medium is supplied in an uncontrolled manner; the effort for monitoring the coupling is thus very high. However, it is also a particular drawback that the adaptation to different tube diameters, and also the adjustment of the insonification angle, is laborious.